Python多线程参数错误

我刚刚开始使用多线程，所以我想让自己成为一个小而简单的示例：

import time
import threading

def count(who):
        count = 1
        while count <= 5:
                print who + " counted to: " + str(count)
                time.sleep(0.1)
                count += 1

thread1 = threading.Thread(target=count, args=('i'))
thread1.start()

效果很好，并打印出以下内容：

>>> i counted to: 1
>>> i counted to: 2
>>> i counted to: 3
>>> i counted to: 4
>>> i counted to: 5

但是，奇怪的是，当我想将参数更改为另一个变量时：“ john”：

线程1 = threading.Thread（target = count，args =（'john'））

希望它将产生：

>>> john counted to: 1
>>> john counted to: 2
>>> john counted to: 3
>>> john counted to: 4
>>> john counted to: 5

但是，它会引发错误：

Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 810, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.7/threading.py", line 763, in run
    self.__target(*self.__args, **self.__kwargs)
TypeError: count() takes exactly 1 argument (4 given)

我真的不确定这里发生了什么...有人知道吗？